Vehicle seat

ABSTRACT

A vehicle seat comprises a synthetic resin cushion plate ( 31 ) attached to a back frame ( 3 ) by way of seat springs ( 32 ) so as to be movable forward or backward, a single elastic auxiliary plate ( 40 ) attached to the cushion plate ( 31 ) so as to be movable forward or backward relative to the cushion plate ( 31 ), a specific section of the auxiliary plate ( 40 ) formed as a push-out section ( 70 ) protruding forward when a distance between an upper edge and a lower edge of the auxiliary plate ( 40 ) is shortened by moving the lower edge upward. Elasticity of the auxiliary plate ( 40 ) supporting the body of the seated passenger is adjusted by moving the auxiliary plate ( 40 ) near the push-out section ( 70 ) forward or backward. The push-out section ( 70 ) has a corrugated part ( 71 ) formed from a sideways projection that projects forward or/and backward as viewed from a side.

TECHNICAL FIELD

The present invention relates to vehicle seats and more particularlyrelates to vehicle seats that have a mechanism for adjusting the cushionpressure.

BACKGROUND ART

A known conventional configuration (e.g., patent document 1) of avehicle seat is such that a single synthetic resin plate capable ofsupporting the back of a seated passenger is attached to a seat backframe for a seat back via wire springs so as to freely move forward orbackward relative to the seat back frame.

Another known conventional configuration (e.g., patent document 2) of avehicle seat is such that an internal structure in the form of aquadrangular frame is fixed to a seat back frame, sideways elasticbending parts are attached to the left and right sides of the internalstructure, a spring plate is disposed between the elastic bending parts,and lumbar supports are disposed on the upper and lower sides of thespring plate via a vertical elastic bending part.

Another known conventional configuration (e.g., patent document 3) of avehicle seat is such that a single synthetic resin plate capable ofsupporting the back of a seated passenger is fixed to a seat back framevia wire springs so as to freely move forward or backward, an adjustingpart movable forward or backward is disposed on part of the plate,thereby adjusting the elastic force for supporting the body of a seatedpassenger.

Patent document 1: JP 2006-21716 A

Patent document 2: JP 11-206506 A

Patent document 3: JP 2006-111066 A

DISCLOSURE OF THE INVENTION

The configuration described in the JP No. 2006-21716 of the knownexamples supports a seated passenger satisfactorily but cannot adjustthe elastic force according to the body type of a seated passenger. Theconfiguration described in the JP No. 11-206506 of the known examplesdecreases cushioning by the rigid body that forms all the four sides ofthe internal structure. Specifically, since the internal structure inthe form of the quadrangular frame is disposed in the quadrangular seatback frame, cushioning in areas other than those providing centrallumbar support decreases.

The configuration described in JP No. 2006-111066 of the known exampleshas the adjusting part in an area of the plate. In order to bend thisadjusting part, the thickness of a specific portion of the adjustingpart is decreased. This narrows the permissible range of plate strength.That is, providing the adjusting part on an area of the plate decreasesthe rigidity of the plate and hence the load supported by the plate.Decreasing the thickness of a specific portion of the adjusting partalso decreases the rigidity of the plate and hence the load supported bythe plate.

It is accordingly an object of the present invention to provide avehicle seat that excels in flexibility according to the body type of aseated passenger.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a vehicle seat.

FIG. 2 is an exploded perspective view of the basic components of theseat back frame and active headrest mechanism of the vehicle seat.

FIG. 3 is a perspective view showing an assembled state from the stateshown in FIG. 2.

FIG. 4 is a perspective view showing a cushion plate and an auxiliaryplate attached to the cushion plate shown in FIG. 3.

FIG. 5 is a side view of the basic components of a side frame of theseat back frame and those of the active headrest mechanism.

FIG. 6 is a perspective view of the cushion plate, the auxiliary plate,and a wire cable.

FIG. 7 is a side view of the cushion plate and auxiliary plate.

FIG. 8 is a sectional view of a push-out section according to anembodiment.

FIG. 9 is a sectional view of a push-out section according to anotherembodiment.

FIG. 10 is a sectional view of a push-out section according to anotherembodiment.

FIG. 11 is a sectional view of an auxiliary plate.

FIG. 12 is a sectional view of an auxiliary plate according to anotherembodiment.

FIG. 13 is a sectional view of an auxiliary plate according to anotherembodiment.

FIG. 14 is a perspective view of an auxiliary plate according to anotherembodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments according to the present invention will hereinafter bedescribed with reference to the accompanying drawings. A vehicle seat 1according to the present invention includes a seat back 2, a seat bottom9, and a headrest 6 disposed on the top of the seat back 2. A seat backframe 3 for the seat back 2 is quadrangular and has a pair of sideframes 17, an upper frame 12, and a lower frame 13. The vehicle seat 1has a cushion 4 covered with a leather member 5.

Disposed near the upper frame 12 is a headrest support 10 extendingsideways and movable relative to the seat back frame 3. Fixed in thesupport 10 are vertical engaging parts 11, into which the lower parts ofthe pillars 8 of the headrest 6 are inserted. The pillars 8 aresupported so that their heights may be freely adjusted by the verticalengaging parts 11.

A bracket 24 is disposed on the upper part of each of the side frames 17or at each end of the upper frame 12. An upper link or bell crank 15 isattached to the bracket 24 so as to freely rotate around a shaft 16.This upper link 15 has a long upper arm 22 extending upward and a shortlower arm 23 extending forward and downward. The upper link 15 is urgedin a clockwise direction by the elasticity of an upper spring 14, asshown in FIG. 5. The spring 14 has first and second ends connected tothe upper link 15 and side frame 17 respectively. The left and rightsides of the headrest support 10 are connected to the correspondingupper arms 22. Each of the lower arms 23 is pivotally fastened to theupper part of a vertically long connection rod 20.

Normally, each upper link 14 is held in the position indicated by asolid line shown in FIG. 5, for example, by means of the elasticity ofthe spring 14 and hence the headrest 6 is held in a standard position aswell. However, if the upper link 15 rotates counterclockwise toward theposition indicated by a dotted line, the headrest support 10 movesforward and consequently the headrest 6 is pushed forward.

Disposed between the side frames 17 is a vehicle rear collision detector25 extending sideways. If the vehicle seat 1 moves forward relative to aseated passenger in the event of a rear collision, the collisiondetector 25 is pushed by the seated passenger and moved backward. Eachside of the detector 25 is connected to a corresponding lower link 26 bymeans of a pin 27, and the lower link 26 is pivotally fastened to thecorresponding side frame 17 by means of a shaft 28. Connected to each ofthe lower links 26 by means of a pin 29 is the lower part of one of thecorresponding rods 20. As shown in FIG. 5, one and the other end of thelower spring 18 are connected to the lower link 26 and side frame 17respectively, thereby urging the lower link 26 in a clockwise direction.Thus, the collision detector 25 is held in its normal front position.

In the event that a rear collision should occur, the collision detector25 is pushed by a seated passenger and moved backward, with the resultthat the lower link 26 is rotated counterclockwise in FIG. 5 and movesthe connection rods 20 downward. At this time, the distance between thepin 29 and shaft 28 is shorter than that between the pin 27 and shaft28. Therefore, the backward movement of the collision detector 25 isefficiently transmitted to the connection rods 20. The downward movementof each rod 20 efficiently moves the corresponding upper link 15counterclockwise, thereby moving the headrest support 10 forward. Inthis case, since the upper arm 22 of each upper link 15 is longer thanthe lower arm 23 thereof, the downward movement of the correspondingconnection rod 20 efficiently moves the headrest support 10 forward.Consequently, the headrest 6 is pushed forward by the forward movementof the support 10 and hence supports the head (or neck) of a seatedpassenger in the event of a rear collision.

Each of the side frames 17 is formed from a metal plate having apredetermined dimension in the forward or backward direction. Atransmission mechanism, which transmits the backward movement of thecollision detector 25 to the headrest support 10, is disposed near theside frames 17. Accordingly, the cushion 4 of the seat back 2 does notinterfere with the movement of the transmission mechanism. A mechanismextending from the shock detector 25 to the headrest support 10 servesas an active headrest mechanism.

As shown in FIG. 4, disposed inside the back frame 3 is a flexiblecushion plate 31. Preferably, the plate 31 is formed from syntheticresin such as polypropylene, and substantially has the form of a singlequadrangular plate. The back face of the plate 31 is supported by seatsprings 32 such as zigzag springs or formed wire springs. The seatsprings 32 are at least an upper seat spring 32A and a lower seat spring32B. As is apparent from FIG. 6, the bent portion 32C formed in themiddle of the lower seat spring 32B is positioned so as to engage withan opening 31A defined in the cushion plate 31. Each of the springs 32extends substantially sideways, and both ends of each are connected tothe corresponding side frames 17 of the seat back frame 3. The upperspring 32A supports an area near the upper edge of the cushion plate 31,and the lower spring 32B supports the middle of cushion plate 31. Thecushion plate 31 is disposed further backward than the seat back cushion4. Engaging the bent portion 32C with the opening 31A enables thecushion plate 31 to be held in the appropriate position by means of theseat spring 32B.

The cushion plate 31 bends upon receiving load from a seated passengerand moves backward against the elasticity of the springs 32, therebyflexibly supporting the seated passenger. The plate 31 supports thecushion 4 with the “plane,” thus ensuring greater safety and comfort fora seated passenger than a conventional configuration in which a cushion4 is supported only by seat springs 32.

The cushion detector 25 is disposed behind the cushion plate 31 with apredetermined space between them. The cushion plate 31 has a plate formso as to broadly cover the back of a seated passenger. In the event of arear collision, the cushion plate 31 moves backward while receiving theload of the seated passenger over a wide area. In this case, the degreeof backward movement of the cushion plate 31 is greatest between thevertical center of the plate and an area just below that. For thisreason, the cushion detector 25 is preferably disposed in a placecorresponding to the vertical center of the cushion plate 31 or in aplace corresponding to the area just below that, so as to securelycushion backward movement of the cushion plate 31.

Such a combination of the cushion plate 31 and collision detector 25yields the desired comfort and a secure hold for a seated passenger, andreliable detection of a rear collision.

Disposed between the seat cushion 4 and the cushion plate 31 is aflexible auxiliary plate 40. Preferably, the auxiliary plate 40 isformed from a synthetic resin, such as polypropylene, and has the formof a single quadrangular plate smaller than the cushion plate 31. Theauxiliary plate 40 is attached to the cushion plate 31 and bendsforward, as shown in FIG. 7, as operated by a seated passenger. Thecushion 4 is pushed forward by the bending of the auxiliary plate 40,thus adjusting the cushion pressure on a seated passenger.

A number of engaging hooks 42 are formed integrally with the upper partof the auxiliary plate 40. The engaging hooks 42 engage with engagementholes 44 formed in the cushion plate 31. The lower part of the auxiliaryplate 40 has a lower engaging part 55 jutting out backward. Locked inthe lower engaging part 55 is a cable head 61 provided for the innercable 57 of the wire cable 56. The wire cable 56 is connected to anoperating section 7 provided for the vehicle seat 1. The lower engagingpart 55 has an accommodating recess 55A in which the cable head 61 canbe accommodated, and a slit 58 through which the inner cable 57 canpass.

Formed in the lower part of the cushion plate 31 is a lower guide slot60, with which the lower engaging part 55 engages so as to slide freely.When the cable head 61 moves upward or downward according to theoperation performed by a seated passenger, the lower engaging part 55 isguided by the slot 60 and smoothly moves vertically without backlash.The appropriate widths of the lower engaging part 55 and slot 60 are setso as to prevent backlash. The cushion plate 31 is provided with a tubeholding part 65 for holding the leading end 63 of an outer tube 62provided for the wire cable 56.

When the cable head 61 is moved upward by a seated passenger operatingthe operating section 7, the lower engaging part 55 smoothly movesupward without backlash while guided by the slot 60. Consequently, theauxiliary plate 40 bends forward (i.e., bulges out), as shown in FIG. 7,so as to push the cushion 4 forward and outward, thus adjusting thecushion pressure on the seated passenger.

By pulling the wire cable 56, the auxiliary plate 40 protrudes forwardand pushes the cushion 4 forward, thereby adjusting the cushion pressureon a seated passenger. However, it is not desirable that the maximumforward projection of the auxiliary plate 40 is vertically affected bypressure, etc., from a seated passenger. For example, while the upperpart of the auxiliary plate 40 may project forward upon the operation ofthe auxiliary plate 40 by a female of relatively lightweight, the lowerpart thereof may project forward upon the operation of the auxiliaryplate 40 by a male of heavy weight. Such an auxiliary plate will notensure the comfort desired by a seated passenger. In order to overcomesuch a drawback, the auxiliary plate 40 is provided with a push-outsection 70 that facilitates forward protrusion of the auxiliary plate40, thus stabilizing the maximum projecting position of the auxiliaryplate 40.

The push-out section 70 according to the present invention has the formof a corrugated or bellows-like plate. Preferably, the push-out section70 has a number of forward projections 72 and a number of backwardprojections 73. The push-out section 70 in the form of the corrugatedplate is notably bendable, compared to the other part of the auxiliaryplate 40. Thus, the push-out section 70 is defined as the maximumforward projections of the auxiliary plate 40. Accordingly, the maximumforward projecting position of the plate 40 stabilizes.

FIG. 9 shows an example where the auxiliary plate 40 has no backwardprojections 73 whereas FIG. 10 shows an example where the auxiliaryplate 40 has no forward projections 72.

Shortening the vertical intervals of the forward projections 72 (or thebackward projections 73) of the auxiliary plate 40 further increase theflexibility of the push-out section 70 to bend. In addition, increasingthe number of forward projections 72 (or the backward projections 73) ofthe auxiliary plate 40 further increases the flexibility of the push-outsection 70 to bend. Accordingly, the shape of the push-out section 70 isdetermined taking into account the required flexibility. The push-outsection 70 is disposed in the appropriate part of the auxiliary plate 40so as to support from the back a part near the lumbar vertebrae of apassenger seated in the vehicle seat 1.

In a representative example of the auxiliary plate 40 shown in FIGS. 8and 11, each of the forward projections 72 and each of the backwardprojections 73 have the shape of an arc of radius of about 1.4 to 6.0millimeters. The back face 74 of each of the forward and backwardprojections 72 and 73 respectively has the shape of an arc of radius ofabout 0.4 to 3.0 millimeters. The thickness of the auxiliary plate 40 isabout 2.0 to 5.0 millimeters, and the thickness of the push-out section70 is about 1.0 to 3.0 millimeters. The distance between the forward andbackward projections 72 and 73 is approximately 3.0 to 15 millimeters.

In the auxiliary plate 40 shown in FIG. 11, the upper part of thepush-out section 70 is a flat area 77. However, as shown in FIG. 12, theauxiliary plate 40 may have above the push-out section 70 a secondbending section 78 of greater flexibility. The second bending section 78smoothly bends the auxiliary plate 40 above the push-out section 70 suchthat the entire bending profile of the auxiliary plate 40 more nearlyapproaches to a desired shape. Accordingly, the auxiliary plate 40ensures outstanding comfort for a seated passenger.

Like the auxiliary plate 40 shown in FIG. 12, an auxiliary plate 40shown in FIG. 13 has a push-out section 70 located in a low positionand, a second bending section 78, in a high position. However, thepush-out section 70 and second bending section 78 in FIG. 13 differ inthe intervals between creases such that the crease intervals of thepush-out section 70 are short and those of the second bending section 78are long. The applied example shown in FIG. 13 can also make the entirebending profile of the auxiliary plate 40 more nearly approach to adesired shape. Accordingly, the auxiliary plate 40 ensures outstandingcomfort for a seated passenger. Each of the forward and backwardprojections 72 and 73, respectively, of the second bending section 78shown in FIG. 13 has the shape of an arc of radius of about 5.0 to 20millimeters.

Strictly speaking, the more appropriate position for the push-outsection 70 is one that changes vertically according to the body type ofa seated passenger. Generally, a big seated passenger prefers thepush-out section 70 to be set in a higher position whereas a smallseated passenger prefers the push-out section 70 to be set in a lowerposition. It is difficult to satisfy both these demands by means of alow cost mechanism. However, even a low-cost mechanism can make theposition of the push-out section 70 more stable. For instance, if thepush-out section 70 is pushed forward by the operation of the operatingsection 7, the push-out section 70 may gradually shift upward ordownward. Such instability is decreased by making the distance K betweenthe upper end of the auxiliary plate 40 and the push-out section 70longer and the distance L between the lower end of the auxiliary plate40 and the push-out section 70 shorter, as shown in FIG. 7.

1. A vehicle seat comprising: a back frame (3) for a seat back (2); asingle synthetic resin cushion plate (31) being capable of supportingthe back of a seated passenger and attached to the back frame (3) by wayof seat springs (32) so as to be movable forward or backward relative tothe back frame (3); a single elastic auxiliary plate (40) attached tothe cushion plate (31) so as to be movable forward or backward relativeto the cushion plate (31); a specific section of the auxiliary plate(40) formed as a push-out section (70) protruding forward when adistance between an upper edge and a lower edge of the auxiliary plate(40) is shortened by moving the lower edge upward, the push-out section(70) being positioned only below a center line of the auxiliary plate(40) so as to support lumbar vertebrae of a person seated in the vehicleseat; wherein elasticity of the auxiliary plate (40) supporting the bodyof the seated passenger is adjusted by moving the auxiliary plate (40)near the push-out section (70) forward or backward; and wherein thepush-out section (70) has a corrugated part formed from a sidewaysprojection that projects forward or/and backward as viewed from a side,said corrugated part being in a maximum forward projection position. 2.The vehicle seat according to claim 1, wherein the corrugated part hasin a vertical direction more than one projection of predeterminedvertical dimension.
 3. The vehicle seat according to claim 2, whereinthe auxiliary plate (40) has a second bending section (78) above thecorrugated part, the second bending section (78) being formed from asideways projection that projects forward or/and backward.
 4. Thevehicle seat according to claim 1, wherein the auxiliary plate (40) hasa second bending section (78) above the corrugated part, the secondbending section (78) being formed from a sideways projection thatprojects forward or/and backward.
 5. The vehicle seat according to claim1, wherein the push-out section (70) has forward projections (72) andbackward projections (73).
 6. The vehicle seat according to claim 1,wherein the specific section formed as the push-out section (70) formsonly a portion of the auxiliary plate (40).
 7. A vehicle seatcomprising: a back frame (3) for a seat back (2); a single syntheticresin cushion plate (31) being capable of supporting the back of aseated passenger and attached to the back frame (3) by way of seatsprings (32) so as to be movable forward or backward relative to theback frame (3); a single elastic auxiliary plate (40) attached to thecushion plate (31) so as to be movable forward or backward relative tothe cushion plate (31); a specific section of the auxiliary plate (40)formed as a push-out section (70) protruding forward when a distancebetween an upper edge and a lower edge of the auxiliary plate (40) isshortened by moving the lower edge upward; wherein elasticity of theauxiliary plate (40) supporting the body of the seated passenger isadjusted by moving the auxiliary plate (40) near the push-out section(70) forward or backward; wherein the push-out section (70) has acorrugated part formed from a sideways projection that projects forwardor/and backward as viewed from a side; and wherein the auxiliary plate(40) has the second bending section (78) above the corrugated part, thecorrugated part having curves each of which is small in verticaldimension and the second bending section (78) having curves each ofwhich is large in vertical dimension.